If your IP is dynamic (changes often) or if you plan to move your computer to another IP, it is recommended to set your TTL to a lower value to minimize this cache time.
For example is the domain for the DNS Made Easy organization. A Fully Qualified Domain Name is the complete name to specify a specific computers location in the hierarchy of a complete domain.
For example there may be two groups within the DNS Made Easy organization; sales and support. If there was a specific system in the support sub-domain, the FQDN for this computer would be computer1.support.
DNS handles the mapping between host names, which we humans find convenient (old and Internet addresses which computers understand for example 192.168.98.2.
A domain name is used to locate an organization or other entity on the Internet.